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Preventing heat illness and heat stroke

By David Pearce, M.D.

Summertime means heat, particularly here in the South. It also is the time for outdoor activities like baseball and football. While staying active and exercising is a great way to stay healthy, activity in the extreme heat of summer carries some risks. Heat stroke and heat illness are dangerous conditions that can affect athletes who exercise in hot environments.

Heat stroke is defined as a life-threatening illness characterized by elevated core body temperature above 104 degrees associated with nervous system dysfunction. This includes nausea, vomiting, dizziness, fatigue, seizures and unconsciousness. Heat cramps can be a precursor and often represent a state of inadequate fluid intake or hydration. Heat stroke carries a high death rate if diagnosis and treatment are delayed. The recent deaths of prominent athletes from heat-related illness have generated significant media coverage and a better awareness of this condition. However, heat-related illness and death are on the rise.

Heat Stroke …
… is a condition were the heat generated by the body overloads the body’s ability to dissipate the heat. The body temperature rises, and a point is reached where the internal functions of the body shut down. During exercise, excessive sweating (an attempt to cool the body) and inadequate fluid intake decrease blood volume. Blood circulation to the skin is the primary mode of cooling, and when blood volume is reduced, so is the ability to dissipate heat.

Diagnosis …
… starts with a heightened awareness when the temperature or heat index climbs above 90 degrees Fahrenheit. Heat stroke is characterized by a core body temperature greater than 104 degrees. The brain is extremely sensitive to temperature. Confusion, one of the first signs of heat stroke, can be associated with dizziness and can progress to delirium, unconsciousness and coma.

Treatment …
… starts with removing the athlete from the hot environment and starting cooling measures. This consists of removing clothing and equipment, fanning and applying cold or ice packs to the neck, groin and arm pits. If able, the athlete should drink fluids with sodium, such as sports drinks. If symptoms persist, take the athlete to an emergency department as soon as possible.

Prevention …
… is the most effective treatment for heat-related illnesses.
  • At the beginning of a strenuous exercise program or after traveling to a warmer climate, initially limit the intensity and duration of exercise, gradually increasing it over 10-14 days to allow time for acclimatization. When this period of time is not available, the length of practice sessions and competition should be shortened.
  • Check environmental conditions before and during practice and adjust schedules accordingly. Avoid practice times during the hottest part of the day, typically 10 a.m. to 5 p.m. Use caution and adjust practice intensity when temperature or heat index rises above 90 degrees. Incorporate rest breaks into practice, making them more frequent as temperature rises. During this rest time, rehydrate and remove participants from radiant heat sources, such as direct sunlight. Use the Wet Bulb Globe Temperature, an index of climatic heat stress, as a guide for exercising in the heat.
  • Begin hydration before the exercise period. Consume 500 ml of fluid two hours before exercise to ensure hydration. Allow time for excretion of excess ingested fluid. Consume another 200-300 ml of fluid 30 minutes before exercise. The recommended fluid intake during exercise is 200-300 ml of cold tap water or a flavored salted beverage every 20 minutes.
  • The type of fluid replacement is dependent on the duration of the event. Plain water is adequate for events lasting less than one hour. For longer events, however, the replacement fluid should contain carbohydrates, sodium and potassium — standard components of commercial sports drinks.
  • Avoid caffeine, particularly in hot weather. Sodas, tea and energy drinks typically contain caffeine or caffeine type products. They increase heart rate and act as a diuretic, which leads to or worsens dehydration.
  • Clothing should be light-colored and limited to one layer of absorbent material to facilitate evaporation of sweat. Replace sweat-saturated garments with dry garments if possible during competition.
  • Weighing athletes before and after practice (particularly during two-a-day football season) to estimate amount of body water lost during exercise is beneficial. This can be used to ensure return to near prepractice weight before next practice. The goal should be to lose no more than 2-3% of body weight during each practice. After exercise, athletes should consume 500 ml of fluid for every pound lost.
Again, the key is prevention. This always begins and ends with hydration.

Beat the Heat

By Jesse Gatlin, Physical Therapist

Summer brings extreme heat and humidity. According to the Centers for Disease Control, more than 300 Americans die every year from heat-related illnesses. When exposed to excessive heat, the body can be unable to properly cool itself, leading to dangerously high body temperatures and medical conditions, such as heat exhaustion and heat stroke. Here are tips to help you avoid a heat-related illness…

• People 65 and older, children, infants and those with chronic medical conditions are the most vulnerable to heat stress.

• Air conditioning is the best protection from heat. During peak sun hours, try to stay indoors. If your home is not air conditioned, visit public facilities, such as shopping malls, libraries or movie theaters to stay cool.

• When outdoors, drink plenty of water to stay hydrated, seek shady areas and take frequent rest breaks from your activity.

• Avoid coffee, alcohol and tea —all contribute to dehydration.

• Wear a hat and loose, light-colored clothing to dissipate heat.

• Recognize the signs of heat stroke: high body temperature, rapid pulse, difficulty breathing, the absence of sweating with hot red and flushed skin, hallucinations, confusion and disorientation.


Heat stroke Q & A

Answered by Chris Hoffman, PT, CertMDT, MPT, ATC

Q: Between 1995 and 2001 how many football players (high school, college and pros combined) died from heat stroke?
A: Aross the United States, 21 football players have died from heat stroke — an average of three athletes per year.

Q: How do you prevent heat-related deaths in sports??
A: Hydration is a key to prevention: Players should be allowed to drink water at any time during their sporting activity, as well as taking frequent cooling-off breaks.

Q: What are the signs of heat-related illness? A: Signs include cool, moist, pale skin (the skin may be red right after physical activity); headache; dizziness; weakness or exhaustion; and nausea. The skin may not feel hot. More serious symptoms include vomiting, decreased alertness level or complete loss of consciousness, and high body temperature (sometimes as high as 105oF). The skin still may be moist or the victim may stop sweating and the skin may be red, hot and dry. Another serious symptom is a rapid, weak pulse and/or rapid, shallow breathing.